Wednesday, August 29, 2012

Converting sewage into potable water

The idea of drinking water recycled
from sewage or wastewater is indeed unsettling if not outright revolting to
most folks. However, in the States, some
communities have no other recourse but to resort to recycled wastewater – El Paso,
Texas and some parts of Los Angeles County and Orange County, California.

Moreover, according to a Wall Street Journal article by Paul Kix, Orange County's Groundwater Replenishment System, which opened in 2008, produces over 70,000 gallons of water every day. It is modeled to a degree on NASA's space station breakthrough: The wastewater goes through a micro-filtration process and then reverse osmosis (in which chemicals, viruses and pharmaceuticals are removed) before being exposed to high-intensity ultraviolet light to destroy any lingering compounds. Over two-thirds of the county has been served by the recycled water system since it went online four years ago, says Michael Markus, the general manager of the Orange County Water District.

Meanwhile, here in Panglao Island, with its
salty water supply, many residents and business establishments have to buy mineral or purified bottled water for drinking
and cooking purposes.

From what I was told, every local barangay
must have its own water purification system, or get its supply of fresh water
from Tagbilaran City. Supposedly, this
issue triggers intense political debates; hence, many barangays, to this day,
are still without a steady supply of fresh water. However, there are residents who are fortunate enough to
have a deep well of fresh water within their property.

Even the prominent resort hotels and
various dining establishments in Panglao are coping with this issue. Most have no alternative but absorb the
additional overhead expense of hiring tankers to deliver fresh water to fill
their water tanks. As for the employees
of the island’s hospitality industry – who rent bed spaces to be near where
they work – a higher fee they must shell out if the boarding house provides
fresh water. But such boarding houses
are a rare find. Salty water is all they
can offer.

Desalination – turning seawater into
drinking water – seems the potential solution, but estimated costs can run
one-half to two-thirds more than for a recycled wastewater facility. That is
largely due to the amount of filtration required: Wastewater has roughly 1,000
parts per million of salt, but seawater has roughly 35,000 parts per million.
Desalination is also, of course, limited to areas near seawater. Hence, Panglao Island is suitable for such.

The WSJ article further points point out that where the programs of recycled
wastewater exist, they are born out of desperation -- which is precisely how
the idea got its start:

Quote

It began in the tiny capsule of the
Mercury rocket, on May 5, 1961, with Alan Shepard looking out his periscope
viewer at the morning clouds. It was 15 minutes before his launch, before he
was to become the first American sent into space, and he was nervous, according
to "Moon Shot," the book that he later co-wrote. The launch director
came on and told Mr. Shepard that there was an electrical glitch; the flight
would have to wait.”

Another problem emerged during the
nearly 90-minute delay: "Man, I got to pee," Mr. Shepard told
astronaut Gordon Cooper, who was in ground control. The flight was only
supposed to last 15 minutes, and the rocket wasn't equipped with a toilet. Mr.
Shepard was told to hold it.

And so the medical team did. A short
while later, Mr. Shepard was launched into his suborbital flight, a brave,
relieved man.

As space flights became longer, the
problem of discarding waste persisted. Neil Armstrong walked the moon in
diapers. It wasn't until the era of the International Space Station, with
astronauts on six-month missions, that NASA engineers began to think creatively
about waste. "We didn't think that we could resupply [the astronauts] with
water up there," says Monsi Roman, a microbiologist at the Marshall Space
Station, who has worked at NASA for 25 years. "And that's when we began to
think about recycling urine for drinking purposes."

Another problem emerged during the
nearly 90-minute delay: "Man, I got to pee," Mr. Shepard told
astronaut Gordon Cooper, who was in ground control. The flight was only
supposed to last 15 minutes, and the rocket wasn't equipped with a toilet. Mr.
Shepard was told to hold it.

And so the medical team did. A short
while later, Mr. Shepard was launched into his suborbital flight, a brave,
relieved man.

As space flights became longer, the
problem of discarding waste persisted. Neil Armstrong walked the moon in
diapers. It wasn't until the era of the International Space Station, with
astronauts on six-month missions, that NASA engineers began to think creatively
about waste. "We didn't think that we could resupply [the astronauts] with
water up there," says Monsi Roman, a microbiologist at the Marshall Space
Station, who has worked at NASA for 25 years. "And that's when we began to
think about recycling urine for drinking purposes."

Urine consists of salt, water and
contaminants, and on the space station today, the salt and contaminants are
distilled and thrown away. The remaining water goes into a processor that burns
away any lingering bacteria, and then iodine further cleans it. "It's a
closed loop," Mr. Roman says—and an inspiration for wastewater treatment
plants back on Earth.

Unquote

Incidentally, about a week ago I
posted a blog article on the success of a team of engineers at Oregon State
University in their study of microbial
fuel cells that generate electricity from wastewater. They have developed a technology that uses
bacteria to harvest energy from the biodegradable components of sewage at a
rate that is 10 to 50 times more efficient than previous methods.

In essence, they are harnessing
biodegradable material in wastewater to feed aerobic bacteria, which digest the
substances with the use of oxygen. When the microbes oxidize these components
of sewage – and, in turn, clean the water -- they produce a steady stream of
electrons.

As the electrons flow from the anode
to the cathode within a fuel cell, they produce an electrical current, which
can be directly used as a power source. Additionally, this process cleans the
water more effectively than anaerobic digestion and doesn’t produce unwanted
byproducts.

Electricity and potable water, in the
near future, might become the most expensive commodities in the worlf
if we do not do something about them now.

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photos appearing on fellow bloggers' sites, popular broadsheets, and local
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